1. Field of the Invention
The present invention relates to an interfacing method in a numerical control apparatus, which is capable of performing an interfacing process at a high speed for signal transfer between microprocessors respectively housed in a numerical control section and in a programmable sequence control section.
2. Description of the Related Art
In a numerical control apparatus of the type having a numerical control section and a programmable control section each of which accommodates therein a microprocessor, various signals are delivered and received, or, transferred, between these processors for execution of various control operations. For example, as shown in FIG. 2, upon completion of reading of a particular command code (an M code, for instance) from an NC program, the processor of the numerical control section, arranged to execute the NC program block by block, delivers a command data to a latch circuit housed in an interface circuit so as to store the same data in this latch circuit. It then sets a predetermined status bit (a status bit MF, for instance) of a register of the interface circuit at a logic level indicative of the command data being stored in the latch circuit. Thereafter, when the sequence control section completes a control operation associated with the command data read out through the interface circuit, the processor of the sequence control section sets a different status bit (a status bit MFIN, for instance) of the interface circuit at a logic level indicative of the control operation being completed. In response to this, the processor of the numerical control section starts execution of the succeeding block only after erasing the command data stored in the latch circuit, if necessary, and resetting the status bit MF. Then, the processor of the sequence control section resets the status bit MFIN. Thus, conventionally, the interfacing process for signal transfer between these processors is time-consuming, resulting in a time period for execution of control being lengthened.